{"id":1499,"date":"2012-11-01T08:48:06","date_gmt":"2012-11-01T13:48:06","guid":{"rendered":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/?p=1499"},"modified":"2012-11-01T13:25:06","modified_gmt":"2012-11-01T18:25:06","slug":"solubility-of-acid-gases-in-teg-solution-part-3-co2-in-teg","status":"publish","type":"post","link":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/2012\/11\/solubility-of-acid-gases-in-teg-solution-part-3-co2-in-teg\/","title":{"rendered":"Solubility of Acid Gases in TEG Solution: Part 3 (CO2 in TEG)"},"content":{"rendered":"

The solubility of acid gases in TEG solution has been the subject of two previous Tips of the Month, (June 2012 and July 2012).\u00a0 In these instances, the focus was on gas streams with maximum acid gas partial pressure of 100 psia (690 kPa) and TEG concentrations of 95 and 100 wt%.\u00a0\u00a0 This is typical for dehydration of sour gas streams.<\/p>\n

This month, the focus shifts to the case where the gas is pure CO2<\/sub>, with partial pressures (and system pressures) ranging up to 800 psia (5 500 kPa), and pure TEG.\u00a0 These conditions approximate the dehydration of high-CO2<\/sub> content gases in a CO2<\/sub> enhanced oil recovery project, or perhaps, CO2<\/sub> from an industrial source that is to be compressed, transported and sequestered.<\/p>\n

Two algorithms have been developed to predict the CO2<\/sub> solubility in pure TEG.\u00a0 One algorithm uses the same format as the Mamrosh-Fisher-Matthews [1] Solubility Model presented in the June 2012 and July 2012 Tips of the Month.\u00a0 In order to improve the correlation for pure CO2<\/sub> and TEG, the equation parameters (A through D) were regressed using data extracted from Figure 20-76 of the GPSA Engineering Data Book [2].\u00a0 The equation and new parameters are presented below.<\/p>\n

In the second algorithm, we propose a 6-parameter empirical equation, which is also regressed from the GPSA Figure 20-76 [2].<\/p>\n

\u00a0<\/strong><\/p>\n

Mamrosh-Fisher-Matthews Solubility Model MODIFIED:<\/strong><\/p>\n

The original Mamrosh et al.<\/em> [1] model, was first applied to data extracted from GPSA Figure 20-76 [2].\u00a0 Average Absolute Percentage Deviation (AAPD) was greater than 6.5% and the Maximum Absolute Percentage Difference for the data set exceeded 34%.\u00a0 To improve accuracy, a multi-parameter regression was performed using data from Figure 20-76.\u00a0 The new values for Parameters A, B, and D (C was set to zero and the original value of E was used) are presented in Table 1 below.<\/p>\n

\"\"<\/a><\/p>\n

Where:<\/p>\n

P<\/em> is the absolute pressure, psia (kPa(a))<\/p>\n

T<\/em> is the absolute temperature, \u00b0R (K)<\/p>\n

xi<\/sub><\/em> is the mole fraction of the acid gas in the liquid phase<\/p>\n

yi<\/sub> <\/em>is the mole fraction of acid gas in the vapor phase<\/p>\n

 <\/p>\n

Note that the mole fraction of water in the liquid ( \u00a0<\/sub>is zero (pure TEG), so parameter \u201cC\u201d has been set to zero.<\/p>\n

Table 1. MODIFIED Parameters for Mamrosh et al.<\/em> model [1]<\/p>\n\n\n\n\n\n
System: Pure CO2<\/sub> in100%TEG<\/td>\n\n

A<\/p>\n<\/td>\n

\n

B<\/p>\n<\/td>\n

\n

C<\/p>\n<\/td>\n

\n

D<\/p>\n<\/td>\n

\n

E<\/p>\n<\/td>\n<\/tr>\n

\n

(FPS)<\/strong><\/p>\n<\/td>\n

\n

7.4188<\/p>\n<\/td>\n

\n

-2727.79<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0.11164<\/p>\n<\/td>\n

\n

0.001864<\/p>\n<\/td>\n<\/tr>\n

\n

(SI)<\/strong><\/p>\n<\/td>\n

\n

9.3508<\/p>\n<\/td>\n

\n

-1515.44<\/p>\n<\/td>\n

\n

0<\/p>\n<\/td>\n

\n

0.008996<\/p>\n<\/td>\n

\n

0.003355<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Accuracy of MODIFIED Mamrosh-Fisher-Matthews Solubility Model:<\/strong><\/p>\n

The accuracy of the MODIFIED Mamrosh et al.<\/em> [1] model was evaluated against the data extracted from Figure 20-76 of Gas Processors Suppliers Association Engineering Data Book, 12th<\/sup> Edition [2]. \u00a0The summary of our evaluation results is shown in Table 2.<\/p>\n

Table 2. Summary of error analysis for MODIFIED Mamrosh et al.<\/em> model<\/p>\n\n\n\n\n
\n

System<\/p>\n<\/td>\n

\n

N<\/p>\n<\/td>\n

\n

AAPD<\/p>\n<\/td>\n

\n

MAPD<\/p>\n<\/td>\n

\n

T Range, \u02daF<\/strong><\/p>\n

(\u02daC)<\/strong><\/p>\n<\/td>\n

\n

P Range, psia (kPa)<\/p>\n<\/td>\n<\/tr>\n

\n

Pure CO2<\/sub> in 100% TEG<\/p>\n<\/td>\n

\n

1018<\/p>\n<\/td>\n

\n

1.85<\/p>\n<\/td>\n

\n

10.08<\/p>\n<\/td>\n

\n

77 \u2013 165<\/p>\n

(25 \u2013 75)<\/p>\n<\/td>\n

\n

15 \u2013 800<\/p>\n

\u00a0(100 \u2013 5500)<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

Where:<\/p>\n

\"\"<\/a><\/p>\n

N<\/em> = Number of data points<\/p>\n

xi<\/sub><\/em>\u00a0 = mole fraction of acid gas in the liquid phase<\/p>\n

Figure 1 presents the data extracted from GPSA Figure 20-76 \u00a0[2]\u00a0 for the solubility of pure CO2<\/sub> in 100% TEG, and the predicted values from the MODIFIED Mamrosh et al.<\/em> equation.\u00a0 GPSA data points are denoted as symbols: Equation results are shown as solid lines.<\/p>\n

Overall the accuracy is very good.\u00a0 At 15 psia, the error looks significant, and the absolute percentage deviation is as high as 10%. However; the actual solubility is small, so the magnitude of the error in physical terms is insignificant.<\/p>\n

Proposed CO2<\/sub> Solubility Model: <\/strong><\/p>\n

A 6-parameter empirical model was developed by regression of the data extracted from GPSA Figure 20-76\u00a0 [2].\u00a0 The general form of the equation is presented as Equation (2) and the values for the six parameters are provided in Table 3.\u00a0 The model is suitable only for pure CO2<\/sub> and 100% TEG.<\/p>\n

\u00a0<\/strong><\/p>\n

 <\/p>\n

\"\"<\/a><\/p>\n

Figure 1 (FPS). Solubility of pure CO2<\/sub> in 100% TEG \u2013 GPSA Fig. 20-76 versus MODIFIED Mamrosh et al.<\/em> Model<\/p>\n

NOTE:\u00a0 Data points from GPSA Fig. 20-76 [2] denoted by symbols: Equation is denoted by solid lines<\/p>\n

\u00a0\"\"<\/a><\/p>\n

Figure 1 (SI). Predicted solubility of pure CO2<\/sub> in 100% TEG \u2013 by MODIFIED Mamrosh et al.<\/em> Model<\/p>\n

\"\"<\/a><\/p>\n

Table 2.\u00a0 Parameters for Moshfeghian model for pure CO2<\/sub> in 100% TEG<\/p>\n\n\n\n\n\n
\n

Units<\/p>\n<\/td>\n

\n

X1<\/sub><\/p>\n<\/td>\n

\n

X2<\/sub><\/p>\n<\/td>\n

\n

X3<\/sub><\/p>\n<\/td>\n

\n

X4<\/sub><\/p>\n<\/td>\n

\n

X5<\/sub><\/p>\n<\/td>\n

\n

X6<\/sub><\/p>\n<\/td>\n

\n

A<\/p>\n<\/td>\n<\/tr>\n

\n

(FPS)<\/strong><\/p>\n<\/td>\n

\n

639.076<\/p>\n<\/td>\n

\n

150.431<\/p>\n<\/td>\n

\n

-2.6482<\/p>\n<\/td>\n

\n

0.01178<\/p>\n<\/td>\n

\n

0.003564<\/p>\n<\/td>\n

\n

2.1731<\/p>\n<\/td>\n

\n

1<\/p>\n<\/td>\n<\/tr>\n

\n

(SI)<\/strong><\/p>\n<\/td>\n

\n

355.042<\/p>\n<\/td>\n

\n

1037.19<\/p>\n<\/td>\n

\n

-2.6482<\/p>\n<\/td>\n

\n

0.01178<\/p>\n<\/td>\n

\n

0.003564<\/p>\n<\/td>\n

\n

2.1731<\/p>\n<\/td>\n

\n

7.4625<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u00a0<\/strong><\/p>\n

Accuracy of the Proposed Solubility Model:<\/strong><\/p>\n

The accuracy of the proposed model was evaluated against the data extracted from Figure 20-76 of Gas Processors Suppliers Association Engineering Data Book, 12th<\/sup> Edition [2]. The summary of our evaluation results is shown in Table 3.<\/p>\n

 <\/p>\n

Table 3. Summary of error analysis for Moshfeghian model.<\/p>\n\n\n\n\n
\n

System<\/p>\n<\/td>\n

\n

N<\/p>\n<\/td>\n

\n

AAPD<\/p>\n<\/td>\n

\n

MAPD<\/p>\n<\/td>\n

\n

T Range, \u02daF<\/strong><\/p>\n

(\u02daC)<\/strong><\/p>\n<\/td>\n

\n

P Range, psia (kPa)<\/p>\n<\/td>\n<\/tr>\n

\n

Pure CO2<\/sub> in 100% TEG<\/p>\n<\/td>\n

\n

1018<\/p>\n<\/td>\n

\n

1.50<\/p>\n<\/td>\n

\n

7.14<\/p>\n<\/td>\n

\n

77 \u2013 165<\/p>\n

(25 \u2013 75)<\/p>\n<\/td>\n

\n

15 \u2013 800<\/p>\n

\u00a0(100 \u2013 5500)<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

Where AAPD and MAPD are as defined above.<\/p>\n

Figure 2 presents the data extracted from GPSA Figure 20-76\u00a0 [2] for the solubility of pure CO2<\/sub> in 100% TEG, and the predicted values from the proposed Model.\u00a0 GPSA data points are denoted as symbols: Equation results are shown as solid lines.\u00a0 Also included in Figure 2 are nine data points from GPA Technical Publication TP-9 [3].\u00a0 These data points are actual values measured for pure CO2<\/sub> and 100% TEG at three pressures. Note the TP-9 data were not used in the regression process.<\/p>\n

The accuracy of the proposed Model is slightly better than the MODIFIED Mamrosh et al.<\/em> model.\u00a0 Average and Maximum Absolute Percentage Deviations are both reduced.\u00a0 As with the MODIFIED Mamrosh et al.<\/em> model, the greatest percentage error corresponds to the low pressure case (15 psia or 104 kPa) where the solubility is very small, so the actual deviation is likely insignificant for most engineering calculations.<\/p>\n

Figure 3 presents the selected data from GPA RR 183 [4] for the solubility of pure CO2<\/sub> in 100% TEG, and the predicted values from the Modified Mamrosh et al.<\/em> Model and the Proposed Model. These GPA data were not used in regressing either of the two models parameters.<\/p>\n

\"\"<\/a><\/p>\n

Figure 2 (FPS)\u00a0 Solubility of pure CO2<\/sub> in 100% TEG \u2013 GPSA Fig. 20-76 versus the proposed model<\/p>\n

NOTES:\u00a0 \u00a0\u00a0 Data points extracted from GPSA Fig. 20-76 [2] denoted by symbols: Equation is denoted by solid lines<\/p>\n

Large Black symbols and solid lines denote data from GPA TP9 [3]<\/p>\n

\"\"<\/a><\/p>\n

Figure 2 (SI)\u00a0 Predicted solubility of pure CO2<\/sub> in 100% TEG by the proposed Model<\/p>\n

\u00a0\"\"<\/a><\/strong><\/p>\n

Figure 3.\u00a0 Comparison of the predicted solubility of pure CO2<\/sub> in 100% TEG at 72.5 psia (500 kPaa) with the GPA RR 183 experimental data [4]<\/p>\n

\u00a0<\/strong><\/p>\n

Conclusions:<\/strong><\/p>\n

Two new algorithms have been developed to predict the solubility of pure CO2<\/sub> in 100% TEG.\u00a0 Both algorithms were developed by regressing data extracted from Figure 20-76 of the Gas Processors Suppliers Association Engineering Data Books [2]. It should be noted that the Figures in GPSA are attributed to Ed Wichert, Sogapro Engineering with all rights reserved.<\/p>\n

The first algorithm is a Modified form of the Mamrosh et al.<\/em> model [1].\u00a0 The original model was presented and evaluated for CO2<\/sub> concentrations of up to 10 mole percent in the June and July 2012 Tips of the Month. However, model predictions for pure CO2<\/sub> and 100% TEG produced an average absolute percentage deviation (AAPD) of more than 6.5%, and a Maximum Absolute Percent Deviation (MAPD) of more than 34% compared with data extracted from Figure 20-76 of the GPSA Engineering Data book [2]. To improve accuracy, the equation parameters were regressed with data points extracted from Figure 20-76.\u00a0 The Modified Mamrosh et al.<\/em> model more accurately reproduces the curves in Figure 20-76, with an AAPD of 1.85% and MAPD of 10.1%.<\/p>\n

The second algorithm, the proposed Model, uses a different form of the equation.\u00a0 The six parameter model was also tuned to match data from GPSA Figure 20-76 [2].\u00a0 The resulting AAPD is 1.50%, and the MAPD is 7.14% compared to Figure 20-76.<\/p>\n

To learn more about similar cases and how to minimize operational problems, we suggest attending our G40<\/strong> (Process\/Facility Fundamentals<\/a>)<\/a>, G4 (<\/a><\/strong>Gas Conditioning and Processing<\/a>)<\/a>, P81 (<\/a><\/strong>CO2<\/sub> Surface Facilities<\/a>)<\/a>, and PF4 (<\/a><\/strong>Oil Production and Processing Facilities<\/a>)<\/a> <\/strong>courses.<\/p>\n

John M. Campbell Consulting (JMCC) <\/em>offers consulting expertise on this subject and many others. For more information about the services JMCC provides, visit our website at\u00a0www.jmcampbellconsulting.com<\/a>, or email us at consulting@jmcampbell.com.<\/p>\n

By: Wes H. Wright \u00a0&\u00a0 Dr. Mahmood Moshfeghian<\/em>\u00a0<\/strong><\/p>\n

Reference:<\/strong><\/p>\n

    \n
  1. Mamrosh, D., Fisher, K. and J. Matthews, \u201cPreparing solubility data for use by the gas processing industry: \u00a0Updating Key Resources,\u201d Presented at 91st<\/sup> Gas Processors Association National Convention, New Orleans, Louisiana, USA, April 15-18, 2012.<\/li>\n
  2. Gas Processors Suppliers Association; \u201cENGINEERING DATA BOOK\u201d Twelfth Edition \u2013 FPS; Tulsa, Oklahoma, USA, 2004.<\/li>\n
  3. Takahashi, S., Kobayashi, R., \u201cThe water content and the solubility of C02<\/sub> in equilibrium with DEG-Water and TEG-Water solutions at feasible absorption conditions,\u201d GPA Technical Publication TP-9, Gas Processors Association, Tulsa, Oklahoma, USA, 1982.<\/li>\n
  4. Davis, P.M., et al.<\/em>, \u201cThe impact of sulfur species on glycol dehydration \u2013 Study of the solubility of certain gases and gas mixtures in glycol solutions at the elevated pressures and temperatures,\u201d GPA Research Report 183 (GPA RR 183), Gas Processors Association, Tulsa, Oklahoma, USA, 2002.<\/li>\n<\/ol>\n

     <\/p>\n","protected":false},"excerpt":{"rendered":"

    The solubility of acid gases in TEG solution has been the subject of two previous Tips of the Month, (June 2012 and July 2012).\u00a0 In these instances, the focus was on gas streams with maximum acid gas partial pressure of 100 psia (690 kPa) and TEG concentrations of 95 and 100 wt%.\u00a0\u00a0 This is typical […]<\/p>\n","protected":false},"author":23,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[3,10],"tags":[],"coauthors":[15,20],"class_list":["post-1499","post","type-post","status-publish","format-standard","hentry","category-gas-processing","category-process-facilities"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p1pQc4-ob","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/posts\/1499","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/users\/23"}],"replies":[{"embeddable":true,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/comments?post=1499"}],"version-history":[{"count":4,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/posts\/1499\/revisions"}],"predecessor-version":[{"id":1511,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/posts\/1499\/revisions\/1511"}],"wp:attachment":[{"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/media?parent=1499"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/categories?post=1499"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/tags?post=1499"},{"taxonomy":"author","embeddable":true,"href":"http:\/\/www.jmcampbell.com\/tip-of-the-month\/wp-json\/wp\/v2\/coauthors?post=1499"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}